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Network Time Protocol or NTP is designed to synchronize a computer to the Internet time servers or other sources, such as a radio, satellite receiver, or a telephone modem service. It can also be used as a server for dependent clients for synchronizing time. It provides accuracy up to less than a millisecond on LANs and up to a few milliseconds on WANs. Typical NTP configurations utilize multiple redundant servers and diverse network paths in order to achieve high accuracy and reliability.


  • NTP 4.2.6 has reached end of support on June 30, 2017. HPE recommends migrating to the latest NTP version 4.2.8 .
  • XNTP 3.5 is no longer supported on HP-UX 11i v3.

About NTPv4:

  • NTP 4.2.8 is the latest version of NTP available on HP-UX 11i v3 operating system.
  • NTPv4 is an implementation of RFC 5905 (Network Time Protocol Version 4: Protocol and Algorithms Specification).
  • NTPv4 also implements RFC 5906 (Network Time Protocol Version 4: Autokey Specification).
  • NTPv4 or NTP version 4 retains backwards compatibility with NTPv3, that is, XNTP 3.5, which is delivered as a part of core on HP-UX 11i v3 operating system.
  • NTPv4 provides significant new features and performance improvements compared to NTPv3.

For more information about the differences between XNTP 3.5 and NTPv4, see the ID mmr_kc-0108724 document  at HPESC.

Table 1: Latest NTPv4 Web release version numbers

Product version number

Operating System

Bundle version number

Release date

NTPv4 HP-UX 11i v3 C. January 2018
NTPv4 HP-UX 11i v3 C. February and March 2017
NTPv4 HP-UX 11i v3 C. February and March 2017
NTPv4 HP-UX 11i v3 C. June 2016

NTP 4.2.8 features:

  • MRU list to monitor the client traffic, include the average time between packets from a given address.
  • Leap smear Approach for handling leap second.

    For more information, see Network Time Protocol (NTP) Release Notes Version 4.2.8 for HP-UX 11i v3, which is available at HPESC .

    NTP 4.2.6 features:

    • NTPv4 supports IPv6 in addition to the default support for the IPv4 address family.
    • The behavior of the daemon during startup is considerably quicker.
    • Interleaved mode, a new feature designed to improve the accuracy by minimizing errors due to queuing and transmission delays, can be used in NTPv4 symmetric and broadcast modes.
    • Huff-n-Puff filter is designed to avoid large errors with DSL circuits and highly asymmetrical traffic when large amounts of data is being transferred.
    • Orphan mode provides an Arialmatic, subnet-wide synchronization feature with multiple sources.
    • The Kiss of Death packet is a new packet rate management tool to help reduce the level of spurious network traffic and protect the busy servers from overload.
    • Burst options burst and iburst send packets temporarily at intervals less than the poll interval and help minimize the network load if the server does not respond.
    • OpenSSL Cryptographic Library has replaced the library formerly available from RSA Laboratories. All 128-bit and 160-bit message digests algorithms are now supported for both symmetric key and public key cryptosystems.
    • NTPv4 includes support for Autokey public-key cryptography for authenticating public servers to clients, as described in RFC 5906.
    • Automatic NTP configuration schemes includes the following:
      • Broadcast/multicast scheme
      • Manycast scheme
      • Server pool scheme
        For more information on configuring Multicast and Manycast schemes, see the document of ID mmr_kc-0114257  at HPESC .
    • Many new options have been introduced for utilities like ntpq and ntpdc, enhancing their functionality. For more information, see the ntpq(1m) and ntpdc(1m) man pages.
    • Slew mode (-x) functioning is more accurate. For more information about configuring NTP for a reliable slew mode (-x), see the ID mmr_kc-0109855 document  at HPESC.
    • Panicgate resolution (-g) for ntpd(1m), when offset is greater than 1000 seconds.
    • Several new NTP configuration options have been introduced. For more information, see the ntp.conf(4)Manpage.
    • The logconfig command can be configured in the /etc/ntp.conf file to control the amount and type of messages written to the system log file or an alternate log file. For more information, see ntp.conf(4) and ntpd(1m)Manpages.
    • Logging, by default, is not turned on. Errors and messages are not logged, unless logging is turned on. For more information, see the ID mmr_kc-0108392 document  at HPESC.


    Table 2 lists the Manpages that are distributed with NTPv4 software depot.

    Table 2: NTPv4 Manpages




    Sets and maintains the system time of the day in synchronism with Internet standard time servers .


    Queries the ntpd daemon about its current state and requests changes to that state.


    Monitors the ntpd operations and determines performance .


    Steps time to synchronize with the server.


    Is the Network Time Protocol configuration file.


    Generates public and private keys.

    Note: To keep backward compatibility, #ntpq -p still shows dispersion (disp). To know the value of jitter, get the association ID using the following command:

    # ntpq -c associations

    Then, use the association ID in the following command to display the value of jitter:

    # ntpq -c  rv <associd> jitter

    The binaries, which were previously xntpd(1m) and xntpdc(1m) have been renamed in this release as ntpd(1m) and ntpdc(1m). Soft links of xntpd(1m) and xntpdc(1m) get created with the new ntpd(1m) and ntpdc(1m) respectively upon installation to prevent the breaking of any existing scripts. The same is applicable to ntpd(1m) startup script, where there is a soft link of /sbin/init.d/xntpd links to ntpd(1m) startup script /sbin/init.d/ntpd..

    How to use xntpd as NTP daemon?

    As by default, the ntpd binary is started, the process name is ntpd.

    To use the xntpd binary, perform one of the following:

    • Use the /etc/rc.config.d/netdaemons file.

      The netdaemons file contains a section defined to set the parameters related to NTP daemon.

      # XNTPD_NAME:specify the daemon name (xntpd or ntpd) export XNTPD_NAME=

    • Use the startup script /sbin/init.d/ntpd.

      /sbin/init.d/ntpd start [daemon name]

      For example,

      /sbin/init.d/ntpd start xntpd

      If the daemon name is given, the ntpd startup script performs the following:

      • Starts the process using the given name.

      • Updates the value of XNTPD_NAME in the /etc/rc.config.d/netdaemons file.

    Warning about an incorrectly formatted restrict command

    The command restrict default mask [noquery/ignore/...] was allowed in xntpd. The default tag already contains a mask So, remove the same from the command line.

    If the command is used in NTPv4, it throws a syntax error and the command does not perform what was intended. The syntax error can be observed in the log file.

    Instead of restrict default mask [noquery/ignore/...], use restrict default [noquery/ignore/...].

    For more information about installing and configuring NTPv4, see Network Time Protocol (NTP) Release Notes Version 4 (NTPv4) for HP-UX 11i v3 at HPESC.
    Additional product information
    Product #: HPUX-NTP
    Version: HP-UX 11i v3
    Software specification: HP-UX 11.31 (HPUX-NTP_C.
    HP-UX 11.31 (HPUX-NTP_C.
    Network Time Protocol Release Notes Version 4.2.8 for HP-UX 11i v3 (762802-008.pdf)